The invention relates to an assembly for an electronic element comprising an electronic module and a hydraulic element of a control device for an automatic transmission of a motor vehicle having a transmission housing partly filled with oil wherein the electrohydraulic control device is situated in the transmission housing at least partly surrounded by oil.
It is known from the practice to dispose a control device for an automatic transmission outside the transmission housing and via lines to connect with the control device control means placed in the transmission housing such as actors or actuators.
However, this solution is disadvantageous in the sense that a long cable routing between the control means and control device is required, an additional space is needed for the control device situated outside the transmission housing.
In U.S. Pat. No. 4,271,728 and in EP 0 697 080 B1, a solution is proposed which solves the problem of the additional space needed by the control device being placed in the oil sump of a transmission, the electric connections between the control electronics and the control means being designed according to EP 0 697 080 B1 as rigid wires.
These known control devices, however, are of difficult access in fitting position and unsatisfactory regarding the arrangement of the components of the control device taking into account the very limited installation space.
In addition, the cooling of the heat-generating control electronics is insufficient in these known transmission controls. The proposed cooling of the control electronics by merely flowing transmission oil around the electronic element proves problematic specifically in operating situations at high temperatures of the transmission oil. Especially in modern automatic transmission, the oil can reach temperatures at which it cannot absorb the amount of heat generated by the electronic components. The consequence of this is an overheating of the electronic components and interruptions in the transmission control which can result in complete failure of the control electronics.
The problem to be solved by this invention is to provide an assembly of an electronic element, comprising an electronic module and a hydraulic element of a control device, for an automatic transmission of a motor vehicle wherein, while saving space, the control device surrounded by oil is disposed in a transmission housing that is of easy access in assembled state and wherein the electronic module of the control device is reliably protected from overheating.
This problem is solved according to the characteristic features of claim 1.
The inventive assembly of the electronic element and of the hydraulic element of the control device and the cooling of the electronic element make possible the utilization of the advantages of an assembly of the control device in the oil sump of the transmission housing with a correspondingly small need of space and short connections of the actuators, the electronic element and, in particular, the transmission central plug being reliably sealed.
Besides, the inventive assembly has the advantage that the construction of the control device does justice to operation and is simple, easy to install and of easy access into the vehicle in assembled state.
The inventive solution also ensures that the power loss of electronic modules is reliably eliminated and the operating temperature thereof is always kept low enough so as to prevent an interruption due to local overheating on an electroplate.
Thereby is not only increased the reliability of the transmission control but the service life of the electronic components is also extended.